Portable conveyor

ABSTRACT

In an improved conveyor of the type including an elongated conveyor-carrying boom pivotally mounted at one end to a wheeled supporting frame, with the other end of the boom being supported by an arm pivotally mounted adjacent the other end of the frame, with a sheave-carrying arm pivotally mounted adjacent the said other end of the support frame, and with a cable passing over the sheave and connected at one end to the support arm and at its other end to an hydraulic cylinder, the sheave arm and support arm are positioned such that the ratio of the reaction force acting on the support arm to the moment arm lying between the support arm pivot point and the point the cable passes over the sheave remains substantially equal for any given position of the conveyor boom. Such a conveyor additionally preferably includes means for adjusting the length of the aforesaid moment arm such that the same structural elements may be employed for booms of varying length.

United States Patent lnventors Charles J. Arndt Valley View, Glen Ellyn;Roy F. Lo Presti, Chicago, Ill. App]. No. 797,647 Filed Feb. 7, 1969Patented Feb. 16, 1971 Assignee llarsco Corporation Harrisburg, Pa. acorporation of Pennsylvania PORTABLE CONVEYOR 16 Claims, 10 DrawingFigs.

US. Cl. 198/1205 865g 21/02 Field ofSearch l98/l 20.5, 121,122,99, 233

References Cited UNITED STATES PATENTS 676,504 6/1901 Kassel 198/1205 3/1930 Neighbour 198/ I 20.5

Primary Examiner-Edward A. Sroka Attorney-Cameron, Kerkam & SuttonABSTRACT: In an improved conveyor of the type including an elongatedconveyor-carrying boom pivotally mounted at one end to a wheeledsupporting frame, with the other end of the boom being supported by anarm pivotally mounted adjacent the other end of the frame, with asheave-carrying arm pivotally mounted adjacent the said other end of thesupport frame, and with a cable passing over the: sheave and connectedat one end to the support arm and at its other end to an hydrauliccylinder, the sheave arm and support arm are positioned such that theratio of the reaction force acting on the support arm to the moment armlying between the support arm pivot point and the point the cable passesover the sheave remains substantially equal for any given position ofthe conveyor boom. Such a conveyor additionally preferably includesmeans for adjusting the length of the aforesaid moment arm such that thesame structural elements may be employed for booms of varying length.

PORTABLE CONVEYOR BACKGROUND OF 'IHE'INVENTION 1. Field of The InventionThe present invention relates 'tolconveyors and more particularly to apower-driven elevator-type conveyor especially designed for use withconcrete mix or the like.

2. Description of the Prior Art While portable boom-type conveyors ofthe elevator type, in which a conveyor supporting boom is pivoted at oneend of a portable frame with the other end of the boom being supportedby a pivotal support arm, have long been known in the art, problems havebeen encountered with reference to the particular manner in which theposition of the support arm (and hence of the conveyor-supporting boom)is adjusted or maintained in static equilibrium. In particular, problemshave been encountered where the position of the support arm ismaintained by a cable passing over a sheave arrangement to a cable drivearrangement. Because of the geometry of the prior art systems, as theconveyor was elevated hydraulic pressure increased, thereby increasing,the tension in the cable. Likewise, the prior structures have not beenusable with conveyor-supporting booms of varying length. It has beennecessary to provide completely different support frame structures forbooms of different lengths.

A further difficulty encountered with prior art devices is that thepreferred endless conveyor belts have not been usable because of theconfiguration booms involved. With such prior structures, it has beennecessary to use a spliced conveyor belt whichis much less desirable. g

Furthermore, such devices have been unsatisfactory in the manner inwhich the conveyor boom is supported in a lowered, rest position in thatthe exact centering of the conveyor on a supporting cradle structure hasbeen achieved only with careful manual manipulation. Yet a furtherdifficulty has been the manner in which the wheels on the supportingstructure have been driven.

SUMMARY OF THE INVENTION The foregoing and other difficultiesencountered with prior power-driven elevator-type conveyors have beenovercome in accordance with the conveyor supporting apparatus of thepresent invention, which comprises: a support frame; a conveyor supportboom pivotally mounted on the support frame adjacent one end thereof,the other end of the boom being free; a support arm pivotally mounted atone of its ends adjacent the other end of the support frame;antifriction means provided at the other end of the support arm, withthe antifriction means adapted to support the free end of the conveyorsupport boom; a sheave arm pivotally mounted at one of its ends adjacentthe other end of thesupport frame; A sheave pivotally mounted at theother end of the sheave arm; cable means fixed at one end to the supportarm, with the cable being passed over the sheave; the other end of thecable means being secured to means for tensioning and adjusting thelength of the cable means; the sheave arm and support arm being locatedsuch that the ratio of the reaction force acting on the antifrictionmeans to the moment arm between the point at which the cable passes overthe sheave and the pivot point of the support arm is substantially equalfor any given position of the conveyor support boom.

In addition, the device preferably includes auxiliary mounting means forthe sheave arm such that by merely varying its mounting point, theaforesaid equilibrium conditions can be maintained for conveyor supportbooms of varying length. In addition, means are preferably provided forsupporting the conveyor boom in its lowered or rest position, includingautomatic centering means for locating the boom in its rest position.

As a result, a primary object of the present invention is to provide aportable elevator conveyor of the character described in which stresseswithin the system are equalized irrespective of the exact position ofthe conveyor boom.

A related object'is to provide a conveyor support structure of thecharacter described which is fully portable and which is fully poweroperated.

Yet another object is to provide a structure of the character describedin which an endless conveyor belt may be quickly and conveniently andremovably positioned in operative relatron.

A further object is to provide a structure of the character describedusing interchangeable parts and the same basic supporting structure forconveyor booms of varying length.

A still further object is to provide a device of the character describedin which improved means are provided for tensioning the conveyor beltsupported by the boom.

DETAILED DESCRIPTION OF THE DRAWINGS panying drawings, in which:

FIG. 1 is a'perspective view of the device produced in accordance withthe present invention;

FIG. 2 is a side elevational view thereof;

FIG. 3 is a plan view of the support frame portion thereof;

FIG. 4 is a fragmentary view, partially in section, taken substantiallyalong line 4-4 in FIG. 2;

FIG. 5 is an elongated fragmentary perspective view of the forward endof the support frame structure;

FIG. 6 is a sectional view taken substantially along line-6 in FIG. 2;

FIG. 7 is a sectional view taken substantially along line 7-7 in FIG. 2;

FIG. 8 is a top plan view of the head section of the conveyor;

FIG. 9 is a top plan view of the tail section of the conveyor with thefeeding hopper removed; and

FIG. 10 is a sectional view taken substantially along line 10-10 in FIG.2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. I and 2 show aportable elevator-type conveyor 20 comprising a support frame assembly22, a boom sa assembly 24, and a power assembly 26. As will hereinafterbe described in detail, boom assembly 24 is pivotable between a loweredor rest position shown in full lines in FIG. I and a raised positionshown in broken lines in FIG. I.

As best shown in FIGS. 2 and 69, boom assembly 24 comprises a mainsection 30, an extension section 32 (see FIG. 2), and an adjustable tailsection 34 mounted on extension section 32 in a manner and for a purposeto be described in detail hereinafter. Main section 30 and extensionsection 32 are of the same general configuration and structure anddiffer only in size and position. Sections 30, 32 are bolted together ina manner that will hereinafter be described in detail.

As best shown in FIG. 6, conveyor extension section 32 comprises fourlongitudinally spaced angles 38, 40, 42, 44 arranged in a generallyrectangular cross-sectional form (see FIG. 6). REspective pairs ofangles 38, 40 and 42, 44 are fixed in position by a plurality ofdiagonally positioned spacer bars 46 (see FIG. 2), the ends of which arewelded to the respective angle pairs. In additional vertical spacerangle 48, 50 (see FIG. 6) is welded in place at one end of section 32and a similar angle (not shown) is welded in position at the other endthereof.

Main boom section 30 is of the same basic overall construction withlongitudinal angles 50, 52 forming one side of the boom and longitudinalangles 53, 54 forming the other side of the conveyor section. Aplurality of bars 56 are welded in position between angles 50, 52 and aplurality of similar bars 57 (see FIG. 5) are welded between angles 53,54in order to stabilize them in position. A pair of vertically disposedend angles 58, 60 (see FIG. 2) further serve to stabilize relativepositions of the respective pairs of side angles.

As best shown in FIG. 9 the respective sides of boom secton 30 arestabilized in position by a plurality of bars 62, the ends of which arewelded to the opposite lower angles of section 30. Similar crossbars(not shown) are provided between the bottom angles 40, 42 of section 32.In addition, generally horizontal angles are welded between therespective longitudinal side angles in order to further stabilize thepositions of the longitudinal angles forming the general configurationof the respective boom sections. Thus, a cross angle 64 is providedbetween angles 50, 54 of boom section 30 and a similar cross angle 66(see FIG. 1) is provided between angles 52 and 53.

As a result, the boom sections of the device of the present inventionare strongly and stably formed by the four longitudinal anglesmaintained in position by welded crossbars and angles.

In order that a problem experienced with portable prior art conveyors atthe point of interconnection of adjacent boom sections may be avoided,as best shown in FIG. 6, a bushing 450 is welded in position behind theface of vertical angles (e.g., angles 48, 50) provided at abutting endsof the adjacent boom sections, and bolts 460 are passed throughrespective pairs of bushing located behind such adjacent spaces in orderto solidly bolt the adjacent boom sections together.

In order to support a movable conveyor belt on the boom assembly 24, aplurality of upper idler roller assemblies 70 are provided betweenangles 50, 54 of section 30 and an additional upper idler assembly 72(see FIG. 8 is provided between upper angles 38, 44 of section 32.Similarly, a plurality of lower idler roller assemblies 74 are providedbetween lower angles 52, 53 of section 30 and lower idler rollerassembly may also be provided for section 32 if desired.

As best shown in FIG. 6, the lower idler roller assembly 74 comprises apair of opposed brackets 76 projecting inwardly from angles 40,4 40, 42,respectively. A pair of upstanding ears 78 are bolted to brackets 76,and ears 78 contain pockets in which the ends of a shaft 80, on which isrotatably carried a lower idler roller 82, are rotatably received. Theother lower idler roller assemblies 74 are of similar configuration.

Each of the upper idler roller assemblies 70, 72 (which are best shownin FIGS. 6, 8, and are removable for a purpose that will besthereinafter appear. As best shown in FIGS. 6 and 8, assembly 72comprises a pair of opposed angle brackets 84, each of which is securedrespectively to one of the longitudinal angles 38, 44 as by the use of aplurality of bolts 83. A pair of V-shaped bars 86 are welded betweenangle brackets 84 (see especially FIG. 8) and bars 86 serve to furtherstrengthen extension section 32. An additional V-shaped bar 88 passesthrough a pair of openings in angle brackets 86, with the end beingsecured in position by retaining pins 90 (see FIG. 6). A pair of upperidler rollers 92 are disposed on the opposed legs of V-shaped shaft 88.Because the ends of V- shaped rod or shaft 88 pass through openings inangle brackets 84, the rollers 92 may be removed and/or changed withoutremoving brackets 84 from the positions in which they are bolted. Theupper idler roller assemblies 70 which are removably positioned on mainboom section 30 are identical to upper idler section 72.

As previously described, a tail section 34 is provided at the end ofboom extension section 32. As shown in FIG. 8, section 34 comprises apair of upper longitudinal angles 94, 96 and a similar pair of lowerlongitudinal angles 98, 99 (see FIGS. 2 and 7). the bottom longitudinalangles are braced in position by welded crossbars 100 (see FIG. 7), andupper longitudinal angles 94, 96 are retained in their desiredconfiguration by a pair of upper idler roller assemblies 102, each ofwhich corresponds in structure and in function to the previouslydescribed upper idler roller assembly 72. Provision is made for slidablemovement of section 34 with respect to section 32, by means of thetelescoping interrelation between the longitudinal angles of the section32 and the longitudinal angles of section 34, for a purpose that willhereinafter appear.

A drive roller 106 is journaled for rotation at the forwardmost end ofsection 34 (see FIGS. 7 and 8, especially). A pair of vertical channels108 are fixed in position between the respective pairs of upper andlower longitudinal channels (e.g., channels 94, 99 shown in FIG. 7), anda pair of bearing assemblies 110 are mounted on angles 108. A shaft 112,on which drive roller 106 is mounted, is journaled for rotation in thetwo bearing assemblies 110. In addition, a drive sprocket 114 is mountedadjacent one end of roller 106 and a drive chain 116 shown in brokenlines in FIG. 2 passes over sprocket 114 and a sprocket 118 of anhydraulic drive motor 119 (see FIG. 7). Suitable hydraulic connectionsare provided between hydraulic motor 119 and power assembly 26, whichincludes selective controls for effecting the driving of drive roller106 via motor 119, chain 116, and sprockets 114, 118. A stabilizing hoop120 is welded in position between longitudinal angles 94, 96 in order tofurther stabilize the end of the tail section 34.

As best shown in FIG. 2, at the lower end of main section 30, a largeend idler roller 122 is journaled for rotation, the mounting of idlerroller 122 being similar to the mounting of previously described driveroller 106 except that a power drive connection is not provided.

A conveyor belt B is passed over the rollers 106, 122 disposed atopposite ends of the boom assembly 24, and the upper train of the belt B(shown in broken lines in FIG. 6) passes over the top of the idlerrollers 92 provided in the various series of upper idler rollerassemblies 70, 72 and 102. The lower train of belt B passes over theupper surfaces of the rollers 82 provided in'the lower idler rollerassemblies 74 pro.- vided along the bottom of boom assembly 74.

In order to properly adjust the tension of the conveyor belt B betweenthe drive roller 106 and the opposite end idler roller 122, the exactposition of extension tail section 98 with respect to extension section32 may be adjusted by telescoping the section 34 in the previouslydescribed manner and then looking the respective overlappinglongitudinal angles in the desired position, in accordance with thebelt-tensioning system described and claimed in J.F. Oury, U.S. Pat. No.3,203,538.

A hopper is mounted over the lower end of the boom 24 at the lower endof main section 32 in order to provide a means of funneling concrete mixor the like onto the belt B, and a discharge chute assembly 132 ispreferably provided at the discharge end of section 34. Briefly, chuteassembly 132 comprises a hood section 134 fixed to hoop 120 and apivotal underlying chute 136 into which the hood 134 directs concretemix. As noted, chute 136 is pivotable in order to move it from awithdrawn transport position (as shown in FIG. 2) to any desired pouringconfiguration, as will be obvious to those skilled in the art.

A belt scraper holder 470 (see FIG. 9) is mounted at the receiving endof boom section 30, and a scraper blade 472 is fixed to support frame470 so as to contact the underside of belt B as it passes over idlerroller 122 at the receiving end of boom section 30, thereby to clean thesurface of belt B prior to its passing under the hopper 130 directingfresh concrete mix or the like onto the moving surface of belt B.

As previously noted, the actual length of boom assembly 24 may be variedby incorporating additional extension sections (similar to section 32shown the drawings). An especially suitable arrangement for the deviceof the character described embodies a basic main boom section 30 32 feetlong with extension sections 32 in additional 8 foot increments up to atotal of 32 additional feet, thereby providing a boom assembly 24 of upto 64 feet in length.

As best shown in FIG. 3, support assembly 22 comprises a generallyT-shaped frame formed by a main longitudinal member (shown in crosssection in FIG. 10) and a transverse member 152 fixed thereto at itsforward end. A pivot bar 154 is fixed to longitudinal member 150 at oneend, and a pair of pivot pins 156 project outwardly from the end ofmember 154 and are adapted to pass through suitable openings in theopposed lower longitudinal channels 52, 53 of main boom section 30 inorder to provide for the pivotal mounting of boom assembly 24 withreference to support assembly 22.

A rear wheel 160 is suitably joumaled in a wheel mounting yoke 162 (seeFIG. 2), which is in turn mounted on a shaft 164 (see FIG. 3) whichpasses rotatably through the rearward end of member 150. A sprocket 166is mounted on the upper end of shaft 164. A chain 168 passes aboutsprocket 166 (see FIG. 3) and about a smaller sprocket 170 provided on ashaft 172 (see FIG. 2) journaled for rotation in a sidewardly projectingbeam 174 (see FIG. 3) which is welded to longitudinal member 160. Acrank arm 176 (see FIGS. 2 and 3) permits a shaft 172 to be rotated viasprockets 164, 170 and chain 168, and thus yoke 162 and the wheel 160may be rotated about a vertical axis thereby serving to steer theconveyor when it is moved. A seat 180 mounted on a seat support 182 isprovided on sidewardly projecting beam 174 in order to provide aconvenient location for an operator to sit.

A pair of sidewardly projecting beams 190, 192 (see FIG. 3) provide abase for a suitable engine or motor 194 which in turn provides a sourceof energy for the conveyor 20 and the operation of the hydraulic powersource 196 which provides the motive force for the operation of theconveyor belt B and the other power features embodied in the conveyor20.

An upstanding car 200 is welded in position on the top edge oflongitudinal member 150, and ear 200 has an opening therein. A pair ofcomplementary ears 202 are provided on the end of an hydraulic cylinder204, and a pivot pin (not shown) passes through ears 200, 202 in orderto provide a pivotal mounting for hydraulic cylinder 204 for a purposethat will hereinafter appear. Cylinder 204 is provided with an actuatingarm 206 which extendsfrom the forward end thereof, and, in response tooperation, may be'extended or withdrawn under hydraulic pressure. Arm206 terminates in a yoke 208 adapted to receive pivotally a cablemounting bracket 210 fixed in position at the end of a cable C providedfor a purpose that will hereinafter appear.

As best shown in FIG. 3, a pair of diagonal angle braces 220 are weldedbetween longitudinal member 150 and transverse member 152 in order tolend stability to the forward end of the support frame assembly 22. Apair of forwardly projecting ears 222 are provided at one side on member152 and a similar pair of forwardly projecting ears 224 are provided ata similar location at the opposite side of member 152. A pair ofupwardly projecting support arms 226, 228 are pivotally mounted betweenthe respective ear pairs 222, 224 by means of pivot pins 230, 232 (seeFIG. 3). Support arms 226, 228 are fixed together by three crossbars234, 236, 238 (see FIGS. 1 and 5) such that arms 226, 228 pivotally movewith reference to the member 152 as a single unit which will be referredto hereinafter as the arm assembly 240. I

A roller 242 (see FIGS. 1 and 2) is journaled for rotation between theends of arms 226, 228, and the ends of roller 242 preferably compriseupstanding flanges whereby the center portion of roller 242 provides anantifriction support surface on which boom assembly 24 may be supportedas shown in FIGS. 1 and 2. Because roller 242 functions as anantifriction support, as the support arm assembly 240 is pivoted theangle of elevation of boom assembly 24 varies, with the respectiveextreme positions of support arm assembly 240 and boom assembly 24 beingshown in full and broken lines in FIG. 1.

The forward (see of cable C is fixed to a turnbuckle 250 (see FIG. 2)which is in turn pivotally attached to the upper end of support armassembly 240 by a pivotal link 252. As a result, when hydraulic cylinder204 is properly actuated and the actuating arm 206 thereofis'hydraulically moved, cable C is either advanced toward the right(whereby under the influence of gravity support arm assembly 240 maypivot downwardly) or toward the left. Support arm assembly 204 is pulledupwardly so as to move boom assembly 204 toward its broken line raisedposition (shown in FIG. 1).

A sheave assembly 260 is provided in order to guide the cable Cintermediate its linking with the arm 206 and the support arm assembly240. As best shown in FIGS. 5 and 10, the sheave assembly 260 comprisesan upwardly projecting plate 262 which is welded to member 150 and whichis provided with a pair of reinforcing angles 264 (see FIGS. 3 and 5).Four openings 266, 268, 270, 272 are provided in one side of plate 262,the precise location of which holes is determined in a manner that willhereinafter be described in detail. A pair of sheave arms 274 arepivotally mounted about a pivot shaft 276 which passes through one ofthe openings 266, 268, 270, 272. The particular opening through whichbottom portion of sheave arms 274 are pivotally mounted will bedetermined in the manner hereinafter described in detail. A sheave 280is pivotally mounted between the upper ends of arms 274, with shaft 282passing through openings in the end of each arm 274 and with sheave 280pivoting thereabout. A groove 284 is provided in the periphery of sheave280 and provides a channel through which cable C passes. Because sheavearms 274 are free to pivot about shaft 276, sheave arms 274 and sheave280 will thus be free to assume the natural position to which it isurged by the cable C depending upon the precise angle at which supportarm assembly 240 is disposed. Normally, sheave arms 274 willsubstantially bisect the angle formed by cable C.

A cradle assembly 290 (see FIGS. 2, 3, and 5) is provided in order toprovide a framework for boom assembly 24 upon which to rest in itslowered or rest position as shown in FIG. I. Cradle assembly 290comprises a pair of side legs 292 formed of metal bar or tubularmaterial which project upwardly and then angle inwardly as best shown inFIG. 5. At the upper end of each side leg 292 is provided V shapd angle294 disposed in a longitudinal direction as shown in FIG. 5. A pair oftubular braces 296, 298 link the respective ends of V-angles 294 andside legs 292 in order to stabilize each side of the cradle assembly290. In addition, a pair of crossbars 300 serve to solidly stabilize therespective sides of the assembly 290. A series of openings 302, 304,306, 308 are provided in the lower end of each side leg 292 (opening 306is not per se shown in the drawings because a pivot bolt 310 whichpasses through a pair of ears 312 and through opening 306 serves toprovide a pivot point about which the cradle assembly 290 may pivot). Asimilar pivotal mounting arrangement is provided for the opposite leg292.

In order to brace cradle assembly 290 in a given angular position, apair of braces 320 are pivotally attached to a lug 322 on cross brace300 by means of a pivot rod 324, the other ends of braces 320 pivotallymounted on plate 262 by means of a pin 326 which passes through one of aseries of openings 330, 332, 334, 336 (opening 332 being obscured in thedrawing). When it is desired to use boom assemblies 24 of greater lengthor when it is desired that the rest position (as shown in FIG. 1) ofboom assembly 24 be higher or lower, the pivotal mounting of legs 292through one of the series of four holes therein may be varied andlikewise the: lower mounting point of braces 320 may be varied in itssimilar select series of four holes provided in plate 262 may likewisebe varied.

In 5 and with the present invention, an especially desirable feature ofcradle assembly 290 is the provision of the V- shaped supporting angles294 (best shown in FIG. 5). A longitudinally positioned anchoring member340 (which preferably takes the form of a metal tube) welded beneath thelower. longitudinal angle 52 of boom section 30 (see FIGS. 2 and 5), anda similar tube 344 is provided beneath longitu dinal angle 53. As bestshown in FIG. 5, members 340, 344 are respectively carried in V-shapedangles 294 when the boom assembly 24 is disposed in its rest position.However, in order that precise centering of the boom assembly 24 on thecradle assembly 290 need not be accomplished in lowering the boomassembly 24 to its rest position, the provision of the outwardlyprojecting sides of V-shaped angles 294- cooperate with the tubularcross section of members 340, 344 to provide for an automatic centeringas the boom assembly 24 is lowered. Thus, precise centering need not beaccomplished, with the angularly disposed sides of angles 294accomplishing this purpose automatically.

As shown in FIGS. l-5, a pair of wheels 350 are provided at therespective ends of transverse member 152. The detailed construction andmanner in which wheels 350 are driven and mounted on transverse mem er152 are best shown in FIGS 4 and 5 Each tire 350 mounted on a wheel 351.which in turn is mounted on a hub 352 Hub 352 IS mounted on an axle 354.on which is provided a drum 356 having a plurality oi sprocket teeth 358disposed thereon Hub 352 is adapted to rotate with respect to axle 354.with hub 352 being fixed to drum 356 so as to rotate therewith Axle 354is welded to a U-shaped bracket 360 having projecting side legs 362, andbracket 360 is bolted to transverse member 152 by a bolt 364 and nut 366which pass through legs 362 of L-shaped bracket 360 and throughtransverse member 152. As best shown in FIG. 3, legs 362 of bracket 360comprise a plurality of radially positioned openings (e.g., openings363). and bolt 364 may be removably passed through different pairs ofopenings 363 in order that wheels 350 may be disposed at any desiredangle.

Wheel 350 is driven by an hydraulic motor 370 which drives a shaft 372on which is mounted for rotation therewith a sprocket 374. A chain 376passes about sprocket 374 and sprocket teeth 358.

Hydraulic motor 370 is mounted on an angle bracket 380 and bracket 380is in turn mounted on a tube 382 which is slidably fitted within asleeve 384 for vertical movement. A bushing 386 is welded in the lowerend of tube 382, and an adjustment bolt 388 is threaded in bushing 386for a purpose that will hereinafter appear. Bolt 388 is journaled forrotation in a sleeve 390, and a ratchet connection 392 and a ratchethandle 394 are provided at the lower end of bolt 388 in order to rotatethe same. By rotating bolt 388 bushing 386 and hence tube 382 may beadjusted vertically so as to adjust the vertical position of hydraulicmotor 370. As a result, the tension on drive chain 376 may be preciselyadjusted merely by operating ratchet handle 394 in order to quickly andconveniently provide the desired degree of chain tension. Sleeve 390 islikewise bolted in position within a sleeve 400 welded to the end oftransverse member 152. An identical hydraulic drive system and chainadjustment arrangement is provided for the other of the wheels 350.

Suitable hydraulic hose connections for pressurized hydraulic fluid areprovided between the power assembly 26 and hydraulic motors 370,hydraulic motor 119, and hydraulic cylinder 204. A control panel 410(see FIG. 1) may be provided in order to give the operator convenientcontrol of all of the power options provided on the device.

In order that appropriate support is given to the elongated boomassemblies (i.e., a boom assembly to which additional extensionsections, such as section 32, have been added), ad ditional insertsections in the longitudinal member 150 may desirably be provided. Theminimum length is shown in FIG. 2 in which member 150 comprises a mainsection 150' and an extension section 150 bolted together at a joint151. FIG. 1 shows a conveyor in which an additional extension section150" has been interposed between sections 150' and 150'. in general,where an extension section (such as section 32) is added to boomassembly 24, it is unnecessary to add any extension sections to member150. However, for each successive extension section added to the boomassembly 24, an additional extension section (such as extension 150")should be interposed as a part of member 150.

In operation, once the appropriate configurations of the boom assemblies24 and the member 150 have been satisfactorily chosen and the correctmounting positions for the cradle mounting assembly 290 and the sheaveassembly 260 have been ascertained, in accordance with the hereinafterto be described principles of operation, an operator sitting in the seat180 can by manipulating appropriate hydraulic controls on the controlpanel 410 cause the boom assembly 24 to move either upwardly ordownwardly between its extreme positions (as shown in FIG. 1) andlikewise by operating hydraulic motors 370 may cause the portableconveyor to advance either forwardly or rearwardly, with steering beingaccomplished by manipulating handle 176, all as previously described indetail.

Because of the geometric relationship between the support arm assembly240 and the sheave assembly 260. stresses throughout the portableconveyor and particularly throughout cable C are maintainedsubstantially uniform. More particularly, the geometry of thearrangement lS such that the ratio of the reaction force acting onantifriction roller 242 to the moment arm between the point at whichcable C passes over sheave 280 and the pivot point for support armassembly 240 (Let, the perpendicular distance between the point denotedby the lead arrow from reference character X and a line passing throughthe pivot points identified by the reference character y as shown inFIG. 3) is maintained substantially equal for differing angularpositions of boom assembly 24. Thus for all positions of boom assembly24, the apparatus satisfies the expression where F is the reaction forceacting on roller 242; where M is the perpendicular distance between aline passing through points Y and a parallel line passing through pointX; and where K is substantially constant.

In other words, as boom assembly 24 changes its position and thereaction force on roller 242 changes, the pivot of sheave arms 274 aboutpivot point 276 results in a change in the aforesaid moment arm suchthat the substantially constant ratio is maintained. Because of thedifferences in the reaction forces acting on the antifriction rollermeans 242 with boom assemblies 24 of differing lengths, the moment armdistance must likewise be changed, and this is achieved by positioningpivot point 276 through a different one of the openings 266, 268, 270,272 in order to vary the desired moment arm distance and so that theequilibrium expression may be obtained for various angular positions ofboom assembly 24. Also, the length of member is appropriately adjusted.In this manner, stresses within cable C are equalized and the likelihoodof operational failures due to unbalanced stresses within the cable Care absolutely minimized.

We claim:

1. Supporting apparatus for a conveyor for concrete mix and the likecomprising:

a support frame;

a conveyor support boom pivotally mounted on the support frame adjacentone end thereof, the other end of the boom being free;

a support arm pivotally mounted at one end adjacent the other end of thesupport frame, the other end of the support arm being adapted to supportthe free end of the conveyor support boom;

a sheave arm pivotally mounted 0 at one end about a pivot point adjacentthe other end of the support frame;

a sheave pivotally mounted at the other end of the sheave arm; and

cable means fixed at one end to the support arm and at the other end tomeans for moving the cable means, with the cable means being passed overthe sheave;

the sheave arm and support arm being relatively positioned such that theratio of the reaction force acting on the support arm to the moment armlying between the point at which the cable passes over the sheave andthe pivot point of the support arm is substantially equal for any givenpivotal position of the conveyor support boom.

2. Supporting apparatus, as claimed in claim 1, wherein the .conveyorsupport boom comprises a main section and a tail section, with thesections being telescopically mounted endto-end whereby to adjust thetension of a conveyor belt carried by said boom.

3. Supporting apparatus, as claimed in claim 2, wherein the length ofthe conveyor support boom is increased by the provision of at least oneextension section interposed between the main section and the tailsection.

4. Supporting apparatus, as claimed in claim 3, wherein the length ofthe support frame is increased by the provision of a support frameextension member foreach boom extension section in excess of one.

5. Supporting apparatus, as claimed in claim 4, wherein the position ofthe pivot point for the sheave arm is adjustable in order to lengthenthe said moment arm whereby, for a conveyor support boom of a givenlength, the ratio of the said reaction force to the said moment armremains substantially equal for any given pivotal position of theconveyor support boom.

6. Supporting apparatus, as claimed in claim 1, and further comprisingantifriction means provided at the other end of the support arm on whichthe conveyor support boom rests.

7. Supporting apparatus, as claimed in claim 1, wherein the supportframe comprises: i

a plurality of rotatably mounted wheels, with at least one of the wheelsbeing driven by a chain driven by an hydraulic motor; and i anadjustable telescopic mounting'for the hydraulic motor for adjusting thetension of the chain drive by varying the relative position between thehydraulic motor and the wheel.

8. Supporting apparatus, as claimed in claim 1, and further comprisingcradle means pivotally'mounted on the support frame adjacent the saidother end thereof and adapted to provide a support for the conveyorsupport boom when the conveyor support boom is disposed in a lowered,rest position, the said cradle means including. at least onelongitudinally disposed V-shaped angle generally positioned beneath theconveyor support boom, with at least one generally cylindrical memberbeing mounted beneath the conveyor support boom and generally inlongitudinal alignmen't'with a corresponding V-shaped angle, wherebywhenthe conveyor support boom is pivoted downwardly toward itsrestposition, each cylindrical member cooperates with the correspondingV-shaped angle to self-center the conveyor support boom on the cradlemeans.

9. Supporting apparatus, as claimed in claim 8, wherein the cradle meanscomprises a pair of V-s'haped angles.

10. Supporting apparatus, as claimed in claim 8, wherein the pivotalmounting for the cradle means is adjustable whereby the cradle means maybe disposed in different positions for conveyor support booms ofdifferent lengths.

11. Supporting apparatus, asclaimed in claim 1, wherein the conveyorsupport boom comprises: a

a power-driven drive roller disposed at one end of the conveyor supportboom;

a main idler roller disposed at the other end of the conveyor supportboom; 1

a plurality of upper V-shaped idler roller assemblies removably mountedon the conveyor support boom;

a plurality of lower idler roller assemblies mounted on the conveyorsupport boom; and

an endless conveyor belt disposed about the main idler roller and thedrive roller; I

with the upper train of the belt being supported by the V- shaped idlerroller-assemblies, and the lower train thereof being supported by thelower idler roller assemblies.

12. In a supporting apparatus for a conveyor comprising a support frame;a conveyor support boom pivotally mounted adjacent one end of thesupport'frame, with the other end of the boom being free; a supportflarmpivotally mounted adjacent the other end of the support frame; a sheavearm pivotally mounted at one end about a pivot point adjacent the otherend of the support frame; a sheave pivotally mounted on the other end ofthe sheave arm; and a cable fixed at one end to the support arm and atthe other end to means for moving the cable, with the cable being passedover the sheave, the improvement comprising the pivotpoint for thesupport arm being positioned relative to the pivot point for the sheavearm such that the ratio of the reaction force acting on the support armto the moment arm lying between the point at which the cable passes overthe sheave and the pivot point of the support arm is substantially equalfor any given potential position of the conveyor support boom.

. The improvement, as claimed in claim 12, wherein the conveyor supportboom comprises a main section and a tail section, with the sectionsbeing telescopically mounted endto-end whereby to adjust the tension ofa conveyor belt carried a by said boom.

14. The improvement, claimed in claim 13, wherein the length of theconveyor support boom is increased by the provision of at least oneextension section interposed between the main section and the tailsection.

15. An improvement, as claimed in claim 14, wherein the length of thesupport frame is increased by the provision of a support frame extensionmember for each boom extension section in excess of one.

16. An improvement, as claimed in claim 15, wherein the position of thepivot point for the sheave arm is adjustable in order to lengthen thesaid moment arm whereby, for a conveyor support boom of a given length,the ratio of the said reaction force to the said moment arm remainssubstantially equal for any given pivotal position of the conveyorsupport boom.

1. Supporting apparatus for a conveyor for concrete mix and the likecomprising: a support frame; a conveyor support boom pivotally mountedon the support frame adjacent one end thereof, the other end of the boombeing free; a support arm pivotally mounted at one end adjacent theother end of the support frame, the other end of the support arm beingadapted to support the free end of the conveyor support boom; a sheavearm pivotally mounted o at one end about a pivot point adjacent theother end of the support frame; a sheave pivotally mounted at the otherend of the sheave arm; and cable means fixed at one end to the supportarm and at the other end to means for moving the cable means, with thecable means being passed over the sheave; the sheave arm and support armbeing relatively positioned such that the ratio of the reaction forceacting on the support arm to the moment arm lying between the point atwhich the cable passes over the sheave and the pivot point of thesupport arm is substantially equal for any given pivotal position of theconveyor support boom.
 2. Supporting apparatus, as claimed in claim 1,wherein the conveyor support boom comprises a main section and a tailsection, with the sections being telescopically mounted end-to-endwhereby to adjust the tension of a conveyor belt carried by said boom.3. Supporting apparatus, as claimed in claim 2, wherein the length ofthe conveyor support boom is increased by the provision of at least oneextension section interposed between the main section and the tailsection.
 4. Supporting apparatus, as claimed in claim 3, wherein thelength of the support frame is increased by the provision of a supportframe extension member for each boom extension section in excess of one.5. Supporting apparatus, as claimed in claim 4, wherein the position ofthe pivot point for the sheave arm is adjustable in order to lengthenthe said moment arm whereby, for a conveyor support boom of a givenlength, the ratio of the said reaction force to the said moment armremains substantially equal for any given pivotal position of theconveyor support boom.
 6. Supporting apparatus, as claimed in claim 1,and further comprising antifriction means provided at the other end ofthe support arm on which the conveyor support boom rests.
 7. Supportingapparatus, as claimed in claim 1, wherein the support frame comprises: aplurality of rotatably mounted wheels, with at least one of the wheelsbeing driven by a chain driven by an hydraulic motor; and an adjustabletelescopic mounting for the hydraulic motor for adjusting the tension ofthe chain drive by varying the relative position between the hydraulicmotor and the wheel.
 8. Supporting apparatus, as claimed in claim 1, andfurther comprising cradle means pivotally mounted on the support frameadjacent the said other end thereof and adapted to provide a support forthe conveyor support boom when the conveyor support boom is disposed ina lowered, rest position, the said cradle means including at least onelongitudinally disposed V-shaped angle generalLy positioned beneath theconveyor support boom, with at least one generally cylindrical memberbeing mounted beneath the conveyor support boom and generally inlongitudinal alignment with a corresponding V-shaped angle, whereby whenthe conveyor support boom is pivoted downwardly toward its restposition, each cylindrical member cooperates with the correspondingV-shaped angle to self-center the conveyor support boom on the cradlemeans.
 9. Supporting apparatus, as claimed in claim 8, wherein thecradle means comprises a pair of V-shaped angles.
 10. Supportingapparatus, as claimed in claim 8, wherein the pivotal mounting for thecradle means is adjustable whereby the cradle means may be disposed indifferent positions for conveyor support booms of different lengths. 11.Supporting apparatus, as claimed in claim 1, wherein the conveyorsupport boom comprises: a power-driven drive roller disposed at one endof the conveyor support boom; a main idler roller disposed at the otherend of the conveyor support boom; a plurality of upper V-shaped idlerroller assemblies removably mounted on the conveyor support boom; aplurality of lower idler roller assemblies mounted on the conveyorsupport boom; and an endless conveyor belt disposed about the main idlerroller and the drive roller; with the upper train of the belt beingsupported by the V-shaped idler roller assemblies, and the lower trainthereof being supported by the lower idler roller assemblies.
 12. In asupporting apparatus for a conveyor comprising a support frame; aconveyor support boom pivotally mounted adjacent one end of the supportframe, with the other end of the boom being free; a support armpivotally mounted adjacent the other end of the support frame; a sheavearm pivotally mounted at one end about a pivot point adjacent the otherend of the support frame; a sheave pivotally mounted on the other end ofthe sheave arm; and a cable fixed at one end to the support arm and atthe other end to means for moving the cable, with the cable being passedover the sheave, the improvement comprising the pivot point for thesupport arm being positioned relative to the pivot point for the sheavearm such that the ratio of the reaction force acting on the support armto the moment arm lying between the point at which the cable passes overthe sheave and the pivot point of the support arm is substantially equalfor any given potential position of the conveyor support boom.
 13. Theimprovement, as claimed in claim 12, wherein the conveyor support boomcomprises a main section and a tail section, with the sections beingtelescopically mounted end-to-end whereby to adjust the tension of aconveyor belt carried a by said boom.
 14. The improvement, claimed inclaim 13, wherein the length of the conveyor support boom is increasedby the provision of at least one extension section interposed betweenthe main section and the tail section.
 15. An improvement, as claimed inclaim 14, wherein the length of the support frame is increased by theprovision of a support frame extension member for each boom extensionsection in excess of one.
 16. An improvement, as claimed in claim 15,wherein the position of the pivot point for the sheave arm is adjustablein order to lengthen the said moment arm whereby, for a conveyor supportboom of a given length, the ratio of the said reaction force to the saidmoment arm remains substantially equal for any given pivotal position ofthe conveyor support boom.